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The trend for heavier lifting operations at greater depths is growing and so MacGREGOR part of Cargotec Corporation has developed an ultra-deepwater lifting system that greatly extends the capacity of MacGREGOR offshore cranes

MacGREGOR has developed an ultra-deepwater lifting system using fibre-rope technology that will enable standard MacGREGOR offshore cranes to reach significantly deeper depths than previously possible using a traditional system. MacGREGOR has unrivalled experience in developing marine cargo handling and offshore load-handling solutions, and is part of Cargotec Corporation, the world's leading provider of cargo handling solutions used in local transportation, terminals, ports, distribution centres, and ships.

Svein Erik Halvorsen, R&D director for MacGREGOR Offshore division, says: The technology has been developed to meet the challenge of subsea activities being moved to deeper and deeper waters and therefore the requirement for offshore cranes to handle heavier lifting operations at these greater depths. The MacGREGOR Hydramarine ultra-deepwater lifting system will undoubtedly transform any standard offshore or subsea crane to one of the most powerful load-handling systems yet made.

The new ultra-deepwater lifting system uses a side-mounted frame fixed onto a vessel. This allows the crane to lower a load to a depth of 1,000m, after which the load is transferred to a straight fibre rope and the crane hook is returned to the surface, reattached to the upper end of the fibre rope, and then a new length of up to 1,000m is deployed. This hook-moving sequence can be repeated until the desired depth is reached. As landing heave compensation is enabled through a winch operation using traditional steel cable, spooling and bending the critical fibre rope is avoided. Eliminating these strains on a fibre rope is essential as it is much more fragile and vulnerable to mechanical stress than traditional steel cable.

Traditional offshore cranes are limited, in part, by the weight of the steel lifting wire itself, which reduces the net hook capacity as more and more wire is deployed to reach greater depths. A 150-tonne single-line crane effectively loses 30 tonnes capacity for every 1,000m of wire deployed. At a depth of 3,000m, for example, a 150-tonne single-line crane will only be able to lift 60 tonnes, although the crane winch is handling the full 150 tonnes and the need for active heave-compensation is substantial.

By using the MacGREGOR ultra-deepwater lifting system, a 150-tonne capacity crane would be able to deploy its full load of 150 tonnes down to a depth, for example, of 5,000m. The final heave compensation is achieved by a standard crane winch, eliminating wear and tear on the fibre rope during this critical phase.

As the system does not weaken the fibre rope or present any challenges related to spooling the full load, MacGREGOR is confident that it can now offer a safe and reliable solution for ultra-deepwater load handling, Mr Halvorsen says.

The MacGREGOR ultra-deepwater lifting solution is available as 150-tonne capacity or 250-tonne capacity systems and can be supplied ready for various lengths of fibre rope. It can also be offered as a reduced version, prepared for future upgrades for even deeper locations.

caption: MacGREGOR new ultra-deepwater lifting solution uses a side-mounted frame fixed onto a vessel; it is available as a 150-tonne capacity or 250-tonne capacity system (Visualisation by Maritime Colours)